Conventionally known control devices include those with two CPUs, namely a main microcomputer and a sub microcomputer (for example, see Patent Document 1).
For example, a conventional control device 100A includes a power supply circuit SC configured to output a voltage based on a battery voltage VB outputted from a battery B, a motor driving circuit MD configured to drive a motor M with the voltage outputted from the power supply circuit SC, a switch SW configured to switch the supply to the motor driving circuit MD of the voltage outputted from the power supply circuit SC, a main microcomputer M1 configured to control the switch SW and the motor driving circuit MD, a sub microcomputer M2, and a reset IC configured to control the main microcomputer M1 (FIG. 3).
The main microcomputer M1 and the sub microcomputer M2 included in the conventional control device 100A monitor each other to detect an abnormal condition (out-of-control state).
If the main microcomputer M1 of the conventional control device 100A becomes out of control and abnormally controls the motor M that is the target of the control, the sub microcomputer M2, which monitors the feedback of the operation of the motor M, controls the motor driving circuit MD to stop the motor M based on the monitoring result.
This may cause a problem in that a large time lag is generated between the time when the abnormal condition occurs to the main microcomputer M1 and the time when the motor M stops.
Furthermore, the two-CPU configuration including the main microcomputer M1 and the sub microcomputer M2 of the conventional control device 100A increases the substrate size, and in turn increases the manufacturing costs.